Wheel suspensions in motor vehicles have various bearings and joints depending on the requirements and the function. For example, ball and socket joints are suitable for making possible a relative motion of two components in a plurality of degrees of freedom. Joint units that have elastomer layers to absorb vibrations introduced via the wheel are known as well. Consequently, the properties of the motor vehicle and here especially those of the wheel suspension can be influenced by means of prior-art joint units not only in respect to the wheel guiding in general but also in respect to an increase in comfort.
Joint units in chassis components are highly stressed safety components, which are usually designed according to the “safe life principle,” i.e., in such a way that they are reliable in operation with multiple safety for the entire service life of a motor vehicle. Nevertheless, events or highly unfavorable causal relationships, in which total failure of such joint units may develop, are purely theoretically conceivable. This would be possible, for instance, as a consequence of the wear occurring on the bearing shell or due to the development of corrosion on the ball pivot, because contaminants or water could enter the interior of the joint after failure of the sealing system. The consequence of this could be that a joint unit thus damaged is completely separated, i.e., the connection between the housing and the pivot would separate.
Prior-art joint units comprise a housing and a pivot, the pivot mounted in the housing by means of a spheroidal bearing surface being able to perform a sliding motion within the housing. The spheroidal bearing surface, which may be part of the pivot and can be connected to same in the sense of assembly, is a usual form of bearing geometry in the state of the art. For example, such a joint unit appears from DE-OS 23 50 087 or EP 1 036 280 A1. Since components are connected to one another in such a way that they are movable relative to one another in the prior-art joint units, the taking into account of the wear occurring between the components that are movable relative to one another represents an essential quality feature. Consequently, considerable efforts are made to keep the wear as low as possible over the entire service life of the joint unit or to eliminate it altogether. Prior-art joint units are sealed in a complicated manner for this reason in order to prevent water or contaminants from entering the inner components of the joint. The available solutions are perfected and mostly guarantee the reliable function of the joint units far beyond the service life of the motor vehicle, so that failure of the joint unit can be ruled out.
Nevertheless, it may happen during necessary repair or maintenance work on the wheel suspension of a motor vehicle that parts of the joint unit are damaged inadvertently or in an unnoticed manner. Would this case actually occur, the above-mentioned entry of water and/or contaminants into the interior of the joint unit could not be ruled out with certainty any longer. However, this would lead to a premature, increased wear of the components of the joint unit. Even complete separation of the housing from the pivot would be conceivable in the extreme case. However, such a case must be ruled out for safety reasons. No solutions that could prevent the complete separation of the housing from the pivot have been known in the state of the art so far, so that such a worn vehicle could still be brought to the nearest repair shop, e.g., with an emergency running function.